Modern Average Earth Temperature

Medieval Average Earth Temperature

Some global-warming deniers claim that the average Earth temperature was higher during the Medieval Warm Period than it is now. The following graph shows that the claim is incorrect.

Holocene Average Earth Temperature

Some global-warming deniers claim that the average Earth temperature was higher earlier in the Current Major Interglacial (the Holocene) than it is now. The following graph shows that the claim is incorrect.

The red dots are where glacial deposits exist; many are at the Equator!

The extreme heat after Snowball Earth occurred because of volcanic activity and the fact that the oceans were covered with perhaps a kilometer of ice, such that they could not absorb the greenhouse gases emitted by the volcanoes.

Global warming can disturb this ocean current by melting ice at the poles and thereby decreasing the salinity and, thus, disturbing the sinking. Also, warmer water at the poles carried there from the tropics disturbs the sinking.

This graph shows an estimate of the atmospheric CO2 concentration due to burning fossil fuels and non-fossil-fuels emissions:

This graph shows an estimate of a "least case" total atmospheric CO2 concentration due to burning fossil fuels and non-fossil-fuels emissions plus a background of 275 ppmv before human intervention, with no saturation of CO2 sinks and no triggering of carbon emissions from the ground and oceans.

The blue curve is due to fossil fuels and the background only. The top curve includes all other causes of carbon dioxide emissions.

This graph shows as estimate of a "worst case" total atmospheric CO2 concentration due to burning fossil fuels and non-fossil-fuels emissions plus a background of 275 ppmv before human intervention, with saturation of CO2 sinks and triggering of massive carbon emissions from the ground and ocean.

http://en.wikipedia.org/wiki/Deforestation: "...recent calculations suggest that carbon dioxide emissions from deforestation and forest degradation (excludingpeat landemissions) contribute about 12% of total anthropogenic carbon dioxide emissions with a range from 6 to 17%."

Average Earth Temperature Due to burning fossil fuels and non-fossil-fuels emission

An estimate of the average Earth temperature for the "least case" total atmospheric CO2 concentration shown above, using a climate sensitivity of 3.

An estimate of the average Earth temperature for the "worst case" total atmospheric CO2 concentration shown above, using a climate sensitivity of 3.

Increasing the climate sensitivity to 4 will increase the temperature by about 1C at 2200 and by about 0.8C by 2500.

Global Dimming

There are particulates that human activity and non-human events emit into the atmosphere that cause cooling rather than heating: